Abstract: A self-diagnostic method for an on-board CTIS (10) for sensing system faults and/or vehicle conditions requiring system shut down. Includes a method for preventing operations of the CITS if the pressure in the air tank has not reached a desired minimum when the vehicle speed exceeds a reference speed for a preselected period of time.

Abstract: A self-diagnostic method of for an on-board CTIS (10) for sensing system faults and/or vehicle conditions requiring shut down. The pressure transducer (80) is exposed to atmospheric pressure to determine if the transducer is generating believable input signals to the system controller (88).

Abstract: A tridem rear drive axle system (100) comprising a front-rear drive axle assembly (112) a middle-rear drive axle assembly (22) and a rear-rear drive assembly (24) is provided wherein torque is distributed substantially equally to each of the three rear drive axles. The front-rear drive axle assembly (112) includes a first input shaft (118) for driving the front-rear drive axle gear set and a second input shaft (114) for driving a through shaft (116) drivingly connected to the middle-rear drive axle assembly (22) which is of a standard forward tandem axle design. A transfer case (102) having a first output shaft (108) for connection to the first input shaft and a second output shaft (106) for connection to the second input shaft is provided. The transfer case provides twice the torque to the second transfer case output shaft than is provided to the first transfer case output shaft.

Abstract: A convertible single speed single reduction drive axle (200) convertible to a shiftable two speed planetary double reduction drive axle (10) is provided. The convertible drive axle (200) utilizes a locking gear (204) and locking gear pins (206) with the same components as found in a two speed double reduction axle (10) with the exception of several components such as the sliding clutch gear (94), idler pinion gears (84), high speed clutch plate (90), clutch plate dowel pins (92), idler pinion pins (88), shift fork (112) and thrust washer (126), which are not utilized.

Abstract: An auxiliary transmission unit is connected to the input of a power divider, which power divider is connected between a pair of pinion shafts for respectively driving the front and rear axles of a tandem axle construction. The power divider includes at least one pair of meshing axle gears drivingly interconnected between the pinion shafts for transmitting torque to each of the axles. The auxiliary transmission unit includes a single pair of meshing transmission gears, one thereof being associated with the transmission input shaft and the other being associated with a parallel countershaft. The output of the transmission unit comprises one of the shafts of the power divider.